Originally Posted by
Wildwood
The speed at which air resistance is greater than rolling resistance is far, far, far below 20mph on a road bike with tires pumped hard on a paved surface.
The
total air resistance of the bike+rider is beside the point. What's actually relevant to the question of what width tire is faster at a given speed is the
difference in rolling resistance for different tire widths (which is significant) versus the
difference in air resistance for those same tire widths (which is exceedingly small at low speeds).